1. Technical Field
Example embodiments of the inventive concept relate in general to software-defined networking (SDN), and more particularly, to a method and device for processing an address resolution protocol (ARP) in an SDN environment.
2. Related Art
Software-defined networking (SDN) means a user-oriented network in which a user has control authority regardless of a basic network device such as a router or a switch, etc. and a separate software controller controls a flow of traffic.
OpenFlow is one variety of SDN technology and defines an interface connecting a hardware such as a router and a controller operating in a network operating system (OS), and is a protocol for separating a control plane for controlling how to transmit a data packet through a network from a physical network and interacting with a data plane for data transmission.
The router to which an OpenFlow function is applied is defined as a matching and an operation of a flow table to layer 2 (L2) switching, layer 3 (L3) routing, an access control list (ACL), a quality of service (QOS), etc. The router does not have a function of processing autonomously even in the case of the L2 switching and an address resolution protocol (ARP), and a concept of receiving the flow table from the controller and processing the ARP is not clear.
Meanwhile, a terminal connected to the router has to know a media access control (MAC) address of a server which is a communication target or another terminal in order to perform internet protocol (IP)-based communication. That is, the terminal performs bidirectional communication with the server which is the communication target or another terminal by adding a destination address to the IP packet.
In order to know the MAC address of the server which is the communication target or another terminal, when the terminal makes an ARP request in a broadcast manner, all terminals in a network composed of the same subnet receive the ARP request. A terminal which has the IP address corresponding to the ARP request performs an ARP response by loading its own MAC address, and the terminal which transmits the ARP request receives the ARP response and generates an ARP table, and thus bidirectional communication can be performed.
In the SDN environment, the ARP response should be processed according to a path which is set by the controller with respect to the ARP request of a lower layer terminal connected to the router, but a definition with respect to this process is not clear. Further, there is a problem in which the ARP request packets from every terminal connected to the router are always concentrated to a central controller and thus a load of the controller is increased.
Moreover, in the case of the terminal connected to the router supporting the SDN, there is no method of dynamically allocating an initial IP, and a basic gateway IP for routing is not set. Accordingly, there is a problem in which the router has no choice but to make the ARP request in the broadcast manner like in the same network, and cannot transmit the ARP request to a specific terminal in another network which cannot be reached in the broadcast manner.